An open glass tube is immersed in mercury in such a way that a length of 8 cm extends above the mercury level. The open end of the tube is then…

An open glass tube is immersed in mercury in such a way that a length of $\displaystyle 8$ cm extends above the mercury level. The open end of the tube is then closed and sealed and the tube is raised vertically up by additional $\displaystyle 46$ cm. What will be length of the air column above mercury in the tube now ? (Atmospheric pressure $\displaystyle =76 \mathrm{~cm}$ of Hg)